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**Jamin_00** · 20-05-2013, 08:35 AM

What about those that don't?

Its better to ship without imo and get the user to add on if they require. This is easier to do than if it were the other way around.

**tomatwalden** · 20-05-2013, 10:51 AM

Excuse my ignorance - but why? If an ESC had a EC2 hanging off it for example for BEC usage, if you didn't need it, you simply don't plug anything in to it?

To my naive mind, that seems simpler than having to solder wires into the ESC if you do need an external BEC

**cjcj1949** · 20-05-2013, 11:01 AM

It is a simple option that could be offered at extra cost. You can solder the wires into the esc battery connectors, but a couple of pads on the esc would help. It would be even better if they offered better built in BECS, I'm sure there's a market. The alternative though is to have separate supplies for the servos and the rx/fbl unit. The servos won't mind the occasional peak and will hold position, while the rx/fbl takes much longer to reset/reboot. Two diodes would probably do the job quite well.

**tomatwalden** · 20-05-2013, 12:06 PM

Yup - The Talon90 is the first ESC I've seen with a substantial built-in BEC. For ESCs without an built-in BEC, isn't it a fair assumption that most will want BEC connectivity? Or do many people still use discrete RX packs ?

**tomatwalden** · 20-05-2013, 12:16 PM

Bizarrely, the YGE 90LV ESC has a switching BEC capable of 6A continuous, 12A peak, which sounds OK.

BUT .....

The 90A ESC isn't enough for my 550X, so you would think the 120LV would be right, but its switching BEC is only 3A continuous, 6A peak!

Arrgghhh..

EDIT : I take this back, seems YGE have a new 120LV on the way ... http://www.yge.de/artikel.php?search=yge120lv with a decent BEC!

**scallybert** · 20-05-2013, 02:19 PM

Floating this as an idea.

Depending on the current, you might be able to power the BEC from the LiPo balance conector. I think they're good for a sustained 4A ? [With a switch-mode BEC 4A @ 6S in should give you ~16A @ 6V out.]

I'm open to polite comments as to the advisability of this...

**cjcj1949** · 20-05-2013, 06:57 PM

I don't see a problem with that. Servos take much less current than peak current. So long as you don't get a spark from the capacitor in the BEC charging. You can get very large Capacitors now, up in the Farad range, they might handle the peaks well enough to smooth them out. Having high current devices on the same supply as a spike sensitive device is asking for trouble, unless the reboot time is very short, which it should be if they handle the brownout interrupt well. They might need some nonvolatile memory capable of being rewritten many times, like CMos. Not sure if E2 memory can do that.

You can use a separate cheap microcontroller to keep the servos happy during a reboot though, especially if they are being refreshed at high rate, by filtering the pulse width and ignoring abrupt changes, and possibly monitoring the voltage line.

**Jamin_00** · 20-05-2013, 07:07 PM

Originally posted by tomatwalden View Post

Excuse my ignorance - but why? If an ESC had a EC2 hanging off it for example for BEC usage, if you didn't need it, you simply don't plug anything in to it?

To my naive mind, that seems simpler than having to solder wires into the ESC if you do need an external BEC

Because I would not want anything extra dangling around and if I had to take it off surely this would more difficult and also leaving something exposed where its much easier to just add it after.

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BEC/ESC connectivity

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